You can now overide :default in your project.clj to change what profiles are
active when none are specified. As part of this change, default is no longer
used to for built-in settings; these are now stored in the :base profile.
This makes it possible to override :default while still including the :base
profile.
if a profile value is a vector, then combine the values using
combine-profiles. this allows you to remove duplication by putting
shared configuration in "base" profiles.
